A previous tutorial written by Kris (I think) goes into some detail showing you how to get the best photo pf a PCB. It deals a lot with lighting, and was really leaning toward someone using an SLR (or at least a digital camera).
This resource concentrates on users of mobile (cell) phone cameras.
1 What can go wrong
Many people use their phone because that's what they have handy, or maybe that's what they use as a camera.
Frankly, most images people take on their cameras are pretty poor. They tend to look like this:
Maybe that's an exaggeration, but it's not too far off. Clearly we can't see anything. At the very least you need to crop the image.
People with access to some limited image editing software will occasionally improve on this by cutting out just the bit we need to see.
This is better, but the image is so small that we can't see much.
If you're going to crop the image, start with the highest resolution image available.
Sometimes people will use a digital zoom to try to zoom in on the object of interest.
The end result can often be too pixilated to show any fine detail.
Digital zoom, when over used is not helpful.
Another common mistake is just moving the camera in closer -- too close for the camera to focus.
Notice that along with blur, the phone was not held steady. Blur caused by either of these issues can make for a useless image.
2 Improved Technique
In general, you should hold the phone as steady as possible and take advantage of your phone's auto focus (if it has it).
OK, so let's look at some examples of what you can do.
In this case I'm using a Lumia 1020. This phone has an awesome camera, but I'm not using anything like the full resolution. These images are about as good as you'll get on a pretty normal phone. In face, the Lumia 1020 has a pretty wide angle lens, so other phones can have the advantage.
I'm also using manual focus (yes, I said not to), and I'm hand-holding the phone. Both of these are less than ideal, so you should be able to do better!
Here is the best shot I can get (full frame) from my phone. It is as close as I can get and still have good focus.
That doesn't look a lot better than the first photo (that I made fun of). However notice that it is sharp.
If your camera has a digital zoom, you can use it in moderation. Here's what I get on my phone:
This is a lot better, and we can improve on it by cropping it:
If your phone can do that well, stop here. This should be fine.
4 Close-up "filters"
But what if you can't do this? What you need are some "close-up filters". These ones were a cheap buy from China.
These are 77mm filters. You probably don't need anything that huge. 52mm, or even smaller will probably suffice.
You can see from the filter on the top that these are supplementary lenses.
The name of them is their strength in diopters. I have a 1, 2, 4, and 10 diopter lens. For the technical amongst us, they have a focal length of 1m, 1/2m, 1/4m, an 1/10m.
If you wear glasses and are long sighted, your lenses will have a strength measured in positive diopters (short sighted people have negative diopter strength lenses). If you're long sighted enough your glasses might even work (but then you won't be able to see the phone!)
Here are some full frame shots wit each of these filters, and with some combinations:
+7 (+1, +2, and +4 all stacked up)
+17 (+1, +2, +4, +10 all stacked up)
Notice that stacking filters reduces the contrast (things look grey).
With a bit of a crop (or zoom), the image looks like this:
And after some enhancement of contrast, we get this:
In this last image you can see that there is some distortion from the closeup filters, and that while the top of the board is in focus, the top of the chips is not so much in focus.
Whilst a close-up filter is the option I use, there are other things you can use:
If you're going to buy a close-up filter for your phone, I'd probably suggest a +8 or +10 filter.
- Spectacles (specifically, "reading" glasses)
- A magnifying glass
- A magnifying viewer (like the ones with in-built lights)
- Custom close-up attachment for your phone
The tradeoff is that a stronger filter will let you get closer and magnify more, however it will decrease image quality and affect the geometry more.
The same techniques can be used for standalone cameras, but with them, you may be able to get away with a +2 or +4 if your camera can already focus quite close.
4 Macro mode
Gryd3 makes the very useful observation that many newer phones have a macro mode which allows close-up photographs.
"Lots of newer phones have additional options in the camera to enable 'Macro' mode. This lets you get up nice and close... Just need to be careful then when you do so the taller components don't hide things... so you either need to aim your camera at a different part of the board, or back up a little. The example picture was taken with a Samsung Galaxy S3 indoors on my desk, with a window 2-3 feet to the right with the blinds 3/4 closed and no indoor lighting.
It is less than ideal as the light is low... but as long as you can hold the camera nice and steady, low light can sometimes be compensated for. (Just makes blur happen a little easier)
Might I also add that I have my 1yr old on my lap when I took this picture... and he wanted to see what I was doing while I was taking the picture and would not stay still.. The first picture was a little blurry..."
He submits this image of a Raspberry Pi as an example. Superimposed on this image is the relative size of the board I was photographing.
It would be a smart thing to search for "<your make and model phone> macro photography" for hints.
5 Image editing software
I made reference to adjusting contrast, but Gryd3 improves on this by providing the following specific advice:
"Users can look into 'Gimp' which is a free image editor that has all sorts of controls to take care of color, contrast, keystone... you name it. Very powerful."
I'll add to that some other options:
Using IrfanView's "Image | Auto adjust colours" and "Image | Sharpen" options, Gryd3's already excellent image comes out like this:
- Photoshop - Very powerful, expensive, not simple to use
- Gimp - Very powerful, free, not simple to use
- Picasa - Good for brightness/contrast, not for image geometry. Free, simple interface.
- IrfanView - Simple adjustments and cropping, free, not difficult to use.
- Windows Paint - cropping and annotation (useless for image enhancement), free, simple interface.
Note that for best results you need good even lighting and an already good image (which is a reason I used this one)